The sister of one of America's top fighter pilots said that the Air Force is tarnishing her brother's memory by blaming him for the crash that took his life rather than the plane that cut off his oxygen supply mid-flight -- the same troubled fighter plane that represents a $79 billion Air Force investment with a major defense contractor.

"I'd like to think it's easier to blame Jeff. He's not here to defend himself," Jennifer Haney, sister of the late Capt. Jeff Haney and family spokesperson, told ABC News in an exclusive interview to be broadcast on "Nightline" tonight. "To them, Jeff was a number, it feels like sometimes. But those jets are worth a lot of money."

Today the Air Force officially received the last F-22 Raptor from defense contracting giant Lockheed Martin, completing an order of 187 planes that cost U.S. taxpayers an estimated $79 billion -- meaning that including research, development and production among other costs, each plane has a price tag of more than $420 million.

Despite the Air Force's glowing descriptions of the jet as America's future of air dominance, critics told ABC News the pricey plane was a waste of money in today's combat environment and, more importantly, it could be more of a danger to its own pilots. As an ABC News investigation found, unknown problems with the plane have already contributed to the death of one pilot, the near-death of another and mid-air scares for dozens more.

The F-22 Raptor, America's most expensive fighter, is the subject of an ABC News investigation airing tonight on "World News With Diane Sawyer" at 6:30 p.m. ET and then "Nightline" at 11:35 p.m. ET.

F-22 Pilot Blamed in Fatal Crash After Plane Malfunction

Capt. Jeff Haney was flying the Air Force's next-generation stealth F-22 Raptor on a routine training mission in Alaska in November 2010 when a sudden malfunction cut off his oxygen completely. Capt. Haney never made a distress call but took his plane into a dive and, a little over a minute later, crashed into the winter wilderness at faster than the speed of sound.

After a lengthy investigation, an Air Force Accident Investigation Board could not find the cause of the malfunction but determined "by clear and convincing evidence" that in addition to other factors, Haney was to blame for the crash because he was too distracted by his inability to breathe to fly the plane properly.

But Haney's sister, Jennifer, told ABC News she believes her brother blacked out trying to save himself and said that by blaming him, the Air Force was attempting to deflect attention from an ongoing, mysterious oxygen problem with the costly planes.

"I don't agree with [the Air Force]. I think there was a lot more going on inside that cockpit," Jennifer Haney said. "A cover-up? I don't know. But there's something."

In at least 25 cases since 2008, F-22 pilots have reported experiencing "hypoxia-like symptoms" in mid-air, according to the Air Force. Last year the Air Force grounded the full fleet of F-22s for nearly five months to investigate, but still no one knows what is going wrong, even as the planes are back in the air. Hypoxia is caused by a lack of oxygen to the brain and is characterized by dizziness, confusion, lack of judgment and, eventually, unconsciousness.

In one case before the grounding, a pilot became so disoriented that his plane dropped down and skimmed treetops before he managed to save himself and return to base, an Air Force spokesperson told ABC News. Earlier this week, a top Air Force official told reporters that a "very small number" of F-22 pilots had requested not to fly the plane anymore because of concerns with the oxygen system.

Top officials at the Air Force and Lockheed Martin refused to take part in one-on-one interviews with ABC News for this report, but the Air Force provided a statement in which it says the service is committed to "unparalleled dedication to flight safety."

"Flying America's premier fighter aircraft always entails risk but the Air Force has, and always will, take every measure to ensure the safety of our aircrews while delivering air superiority for the nation," the statement said. The Air Force has also stressed that reports of "hypoxia-like symptoms" are exceedingly rare -- more than two dozen compared to the thousands of flights flown without incident.

The Pentagon had originally ordered hundreds more of the planes from Lockheed Martin, but in 2009 high-powered critics of the program from across the political spectrum -- from Sen. John McCain to President Barack Obama -- pressured Congress to cancel further funding for F-22s beyond the 187 already ordered, saying that the enemy the F-22 was designed to fight -- rival, super-sophisticated fighter jets in great numbers -- simply doesn't exist.

"I think [the F-22] ensures air dominance... but I guess the question that needs to be asked in return is, where is the threat?" Sen. McCain told ABC News recently. "Unless you believe that al Qaeda is going to have a fleet of aircraft…"

Recently, several of the planes have been deployed to a base in the United Arab Emirates just a short hop over the Persian Gulf from Iran in what the Air Force called a regular, scheduled deployment. Last year, the vice president of Lockheed Martin's F-22 program told ABC News the stealth fighter could "absolutely" find a home in quick strike missions against high security targets like North Korea or Iran.

The Air Force has claimed the F-22 is ready to go to war should it be called but also admitted several training operations have been aborted due to the hypoxia concerns.

There are also pointed questions from critics at home surrounding the Air Force's ruling on Haney's crash and whether the service is protecting the fighter program over its pilots.

Just a month after the Air Force's report was made public, the Pentagon Inspector General alerted the Air Force that it would be reviewing the Air Force's investigation -- the first such major crash investigation review conducted by the Pentagon Inspector General since the mid-1990s.

Pierre Sprey, an early fighter jet designer and vocal critic of the F-22, said he has major problems with the Air Force's report.

"From front to back, they're warping every fact you see in that thing, to make sure they will call it pilot error and not to blame Lockheed or not to blame the Air Force or the airplane," Sprey told ABC News. "Here you have a superb pilot and an airplane that wasn't designed to take care of him. And now they're blaming it on him and he shouldn't have died in the first place… The priorities are hardware first, people second."

Steve Ganyard, an ABC News consultant and former U.S. Marine Corps fighter pilot, said that after watching an Air Force computer simulation of the crash obtained by ABC News, he believes Haney was unconscious at least part of the time.

Flight data reflected in the simulation video shows that before the crash, for a period of 15 seconds straight, Haney virtually does not make any movements at the controls, all the while rocketing nearly straight down towards the ground. Haney did apparently try to pull up at the last moment, but it was too late.

"He wasn't touching any of the controls and just continuing to go at the ground at almost 700, 800 miles per hour," Ganyard said. "I think that [the Air Force's] conclusions are debatable at the very least... I just cannot believe that this pilot, as good as he is, knowing that the airplane is in an extreme position, is still conscious."

That was the conclusion that two pilots in Haney's squadron in Alaska -- including one that was flying another plane during Haney's fateful last mission -- came to well before the Air Force completed their investigation.

"The only thing I can come up with is by all indications, he was full up and, no kidding, a minute later he flew the jet in the ground nearly straight down," Haney's squadron commander told Air Force investigators, according to an extended version of the Air Force investigation report obtained by ABC News through a Freedom of Information Act request. "And the only thing that makes sense to me in that situation -- without a radio call -- is that he was somehow incapacitated."

"As far as I can think, there was definitely something that made him incapacitated at some point. I just can't think of what," said the pilot who was on the training mission.

The extended report also showed that Haney was an exceptional pilot, spoken of in glowing terms by fellow pilots and superiors alike.

Widow Files Lawsuit, Air Force Defends Report

Anna Haney, Jeff's wife, filed a lawsuit against Lockheed Martin and several defense contractors involved in the plane's production for wrongful death, claiming that Lockheed and the others purposefully sold the Air Force a plane they knew was defective and put her husband in harm's way. Jeff is survived by Anna and their two daughters.

In response to Anna Haney's lawsuit, Lockheed Martin said that while the loss of Capt. Haney was a "tragic event," the company "does not agree with those allegations and... will respond to them through the appropriate legal process."

Multiple top Air Force officials said that they stand by the investigation board's findings and believe Haney was awake and just too concerned with pulling a ring to activate his emergency oxygen system -- one that the Air Force has since redesigned to be more accessible -- to notice he was flying straight down in the middle of the night.

"When you have an emergency, you are focused on that emergency and there are times when we are susceptible and vulnerable to over-channelizing our efforts," said Maj. Gen. Noel Jones, a former F-16 pilot and current Air Force Director of Operational Capability Requirements at a press briefing in March. "So the reconstruction of what the aircraft was doing, the inputs to aircraft controls made the [investigative] board believe that [Capt. Haney] was not incapacitated and it ultimately was [disorientation]."

The commander of the Air Force's Air Combat Command, Gen. Mike Hostage, told reporters earlier this week Haney was "simply presented with a series of circumstances that he was unable to overcome."

"The people who know and love Jeff know better," Jennifer Haney said. "We know that Jeff, whatever was going on inside that cockpit, Jeff did everything he was capable and trained to do until he was unable to do any more.

"I know that the Air Force has said that they were very proud to have Jeff and are very sorry for our loss -- well then, in Jeff's name, fix this," she said. "We want to make sure Jeff did not die in vain -- that his death will mean something and that if it saves lives of pilots now, future pilots, then he died for the greater good or something."

After an Air Force scientific board's investigation into the mystery problem that also failed to pinpoint a "smoking gun," the Air Force began to enact changes to the plane recommended by the board, including improving the emergency oxygen system.

But for all their effort, the Air Force still doesn't have what Jennifer Haney said is most important both to her family and to the families of pilots that risk their lives every day at the controls of the F-22: answers.

"I believe Jeff deserves that. That was my baby brother and I believe he deserves that. He deserves the truth to be told as to what happened. Not anybody's guesses," she said. "He deserves the truth. He deserves honor and so do his little girls."